1. Field of the Invention
The present invention relates to door locks, particularly mortise locks, in which a trim mechanism mounted on the surface of the door has a handle turning a spindle that extends into the door to operate a lock mechanism mounted therein. More specifically, the present invention relates to a preassembled integrated trim assembly having a retracting spindle that extends between the trim mechanism and the lock mechanism to accommodate varying door thicknesses.
2. Description of Related Art
Mortise locks typically have a pair of trim mechanisms mounted on opposite faces of a door to operate the lock mechanism mortised into the door. The lock mechanism includes a latchbolt that engages the strike plate on door frame to latch the door closed and the trim mechanisms include corresponding handles that allow the user to open the door by retracting the latchbolt when the door is unlocked.
In this type of design, the retraction of the latchbolt into the lock mechanism is achieved by operating a handle which turns a spindle extending from the trim mechanism to the lock mechanism. Different types of handles may be incorporated into the trim mechanism, such as lever handles, conventional knob handles, and paddle handles, etc., depending upon the intended use of the door. Knob handles are commonly used in private buildings. Lever handles are often used in public buildings and paddle handles are often found in hospitals or other locations where it is desirable to operate the door without grasping the handle with the hand.
In lever handles and knob handles, the spindle is usually turned directly by the handle. Rotating the handle turns the spindle which operates the lock mechanism. In paddle handles, there is a linkage or cam mechanism that converts an inward motion of the handle to spindle rotation. The subject invention is applicable to any type handle and for convenience the following description will be directed to lever handles.
In mortise locks, the lock mechanism is typically mounted halfway between the two opposed faces of the door (at the midplane of the door), and the handle trim mechanisms are surface mounted on the opposed faces of the door. Because doors can have different thicknesses, the distance from the face of the door to the midplane of the door will vary. Accordingly, the length of the spindle also varies, as it must correspond to the thickness of the door. The correct length for the spindle is particularly important for mortise locks that are designed with a pair of independent coaxial spindle hubs. This design allows handles on opposite sides of the door to be locked and operated independently.
With a pair of independent spindle hubs, the hubs are symmetrically located within the lock mechanism on opposite sides of the midplane of the door and the spindle from each trim mechanism cannot extend past the door midplane. If a spindle is too short, it will not fully engage its corresponding spindle hub. Alternatively, if the spindle is too long, it will bind and may jam the locking mechanism or the trim mechanism. The spindle length must be correct for the door thickness.
The need to match the spindle length to the door thickness is inconvenient, as the installer of the door lock must know the thickness of the door. It is also inconvenient for the supplier who must supply multiple spindles to match different door thicknesses or require that the purchaser specify the door thickness when the lock is purchased. Errors in selecting and installing the correct spindle are common and result in locks that jam, bind or fail to operate correctly. A related problem is that removable or replaceable spindles may fall out during handling or become misplaced before or during installation.
It is also desirable to provide an integrated trim assembly which is pre-assembled and factory adjusted. The integrated trim assembly incorporates a decorative cover (rosette or escutcheon), a mounting plate, through bolt posts, a retractable spindle and a handle (lever or knob). Such an assembly enables ease of installation, avoids field adjustment and less error during installation. FIG. 9 for example, shows a typical prior art trim assembly comprising a number of parts which must be assembled during installation or installed separately.
The present invention relates to solving the above problems where the lock mechanism is mounted in the door and has at least one surface mounted trim mechanism on the surface of the door. It is generally directed to the case where the trim mechanism has a spindle which cannot extend beyond some maximum depth, to prevent binding, but must extend to at least some minimum depth to properly engage the lock mechanism, and, more specifically, to a mortise lock having independent coaxial spindle hubs.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a spindle trim mechanism for operating a door lock which spindle automatically retracts to accommodate different door thicknesses.
It is another object of the present invention to provide an automatic retracting spindle trim mechanism for operating a door lock in doors of different thicknesses and which comprises an integrated assembly which may be pre-assembled and does not have separate loose parts.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.